F-15X: USAF Seems Interested

Military aircraft - Post cold war aircraft, including for example B-2, Gripen, F-18E/F Super Hornet, Rafale, and Typhoon.
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sprstdlyscottsmn

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Unread post20 Mar 2020, 16:03

mixelflick wrote:An entire range of AMRAMM/AAM carriage possibilities are being modeled for the F-15EX. Witness what's pictured below. This would allow carriage of up to 16 AAM's alone, and that's before adding 4 more on weapons station 1 and 9, and leaves the centerline weapons station open (potentially up to 4 more AMRAAAM's on a quad launcher).

So I can see provisions for up to 24 AAM's, although in practice I'd expect no more than 12-16 to be carried at most. Whatever the case, the F-15EX will have the ability to carry more AAM's than any other US fighter.

That is the first time I have seen the two-packs on the body other than a render. I have been informed that stations 1 and 9 are limited to 750# payload. That's two AMRAAMS, not four, so that would be a 20 AAM max load, which still sounds ridiculous.
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eagle3000

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Unread post20 Mar 2020, 17:41

weasel1962 wrote:Pictures talk. Boeing strengthened the frame for later F-15s to allow the use of stations 1 & 9, which is something the F-15E can't do but the EX can. That's not just single missiles but including the dual/triple/quad launchers (as highlighted by mixelflick). As to CFT not optimised for A2A, note the AAMs on the CFT stations...


No strengthening was required in case of stations 1/9 - these exist since the earliest A/B model days.
Non-fly-by-wire Eagles don't use them because there are stability issues.
No quad racks on stations 1/9 - 2 AAMs or 1 HARM is all they're cleared for.

And as mentioned, type 4/5 CFTs are not optimised for A/A, but A/G. Doesn't mean they can't carry AAMs. They even can store the LAUs for AAMs whilst carrying the BRUs for bombs. Meaning each CFT is equipped with 6 BRUs and 2 LAUs at the same time. When loading AAMs, the forward BRU swaps places with the forward LAU.
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eagle3000

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Unread post20 Mar 2020, 17:46

weasel1962 wrote:Can the F-15C CFTs be used on the E?

As to pylons, I believe this can be removed as well.


Not as such, as the more powerful engines require larger cooling intakes.
So there would be some mods needed.

I don't think the CFT pylons can be removed. I mean for maintenance, probably. But not for flying.
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eagle3000

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Unread post20 Mar 2020, 17:54

mixelflick wrote:An entire range of AMRAMM/AAM carriage possibilities are being modeled for the F-15EX. Witness what's pictured below. This would allow carriage of up to 16 AAM's alone, and that's before adding 4 more on weapons station 1 and 9, and leaves the centerline weapons station open (potentially up to 4 more AMRAAAM's on a quad launcher).


The centerline does not carry AAMs.
At least not currently. With the amber rack, it would be 2 at most. There is only 1 centerline station.

So the maximum load is 20 AAMs.
That is with amber racks, which look draggy, and the A/G CFTs are already draggy.
16 AAMs without the amber racks.

Personally, I'd ditch the draggy (and heavy!) CFTs and carry 2 or even 3 drop tanks for 12 missiles max.
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madrat

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Unread post20 Mar 2020, 18:37

The E version of CFT is still less drag than externally carried fuel loads. I have no idea what you would gain with elimination of CFT...
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rowbeartoe

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Unread post20 Mar 2020, 18:47

madrat wrote:The E version of CFT is still less drag than externally carried fuel loads. I have no idea what you would gain with elimination of CFT...


Wouldn't drop tanks be better because you could "drop" them when engaging in combat?
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Unread post20 Mar 2020, 18:55

rowbeartoe wrote:
madrat wrote:The E version of CFT is still less drag than externally carried fuel loads. I have no idea what you would gain with elimination of CFT...


Wouldn't drop tanks be better because you could "drop" them when engaging in combat?

What restrictions do they impose? None. What do you need to fly at maximum effectiveness? Energy. So you're just going to punch off fuel that imposes no maneuvering restrictions so you can have less energy available? Not seeing your sense here.

My argument regarding CFT was that they chose a less optimized for A2a version and are supposed to believe the USAF is buying F-15EX that is optimized for A2A. If that emotional argument was true then the F-15EX would have CFT that was truly less drag and optimized for streamlined AIM-120 carriage. It is not, therefore their arguments for needing F-15EX sound dubious.
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Unread post20 Mar 2020, 21:26

madrat wrote:The E version of CFT is still less drag than externally carried fuel loads. I have no idea what you would gain with elimination of CFT...


Type 5 CFTs are 4386 pounds and 21.3 drag index. That's a lot, esp. since you can't get rid of it. There's a reason CFTs haven't caught on in F-15C units - and these were lighter and less draggy CFTs.

2 tanks have less fuel than CFTs, 7930 lbs vs 9352 lbs.
But they add only 640 lbs and 11 DI. Not counting the wing pylons since these are there anyway. You will note that's a whopping 3746 lbs and 10.3 DI less. And you can get rid of it.

3 tanks carry 11895 lbs of fuel vs 9352 lbs.
They add 1259 lbs and 26.5 DI. Including the center pylon. Still 3127 lbs lower weight, but 5.2 DI more - but also more fuel, and you can get rid of everything but the center pylons 299 lbs and 3.3 DI.

With F-15C style CFTs, the situation is a bit different. They're "only" 2487 lbs and DI 4.
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eagle3000

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Unread post20 Mar 2020, 21:30

madrat wrote:What restrictions do they impose? None. What do you need to fly at maximum effectiveness? Energy. So you're just going to punch off fuel that imposes no maneuvering restrictions so you can have less energy available? Not seeing your sense here.


Weight and drag impose huge restrictions on a fighter. Weight and drag kill performance.

madrat wrote:My argument regarding CFT was that they chose a less optimized for A2a version and are supposed to believe the USAF is buying F-15EX that is optimized for A2A. If that emotional argument was true then the F-15EX would have CFT that was truly less drag and optimized for streamlined AIM-120 carriage. It is not, therefore their arguments for needing F-15EX sound dubious.


USAF doesn't want to spend the money needed to develop and certify A/A optimized CFTs.
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Unread post20 Mar 2020, 22:29

And your flight restrictions with EFT under wing limit your operations dramatically. And when you drop EFTs you just punched a big limitation to your remaining time on station. So there is going to be trade-offs no matter which route you choose. But if I'm lugging around 10-12 missiles I'm planning to stay in the fight, not shooting and running.
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weasel1962

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Unread post21 Mar 2020, 02:19

eagle3000 wrote:No strengthening was required in case of stations 1/9 - these exist since the earliest A/B model days.
Non-fly-by-wire Eagles don't use them because there are stability issues.
No quad racks on stations 1/9 - 2 AAMs or 1 HARM is all they're cleared for.


Noted (incl other posters) with thanks. So the requirement is for digital FBW to utilise stations 1&9, which can actually be retrofitted.

Well the CFT pylons can be removed...
f-15.jpg


Wings were strengthened.
https://www.flightglobal.com/helicopter ... 93.article

Just as important are the bells and whistles. I would think the software improvements are a step up even for A2A missions (even without the CFTs).
https://www.thedrive.com/the-war-zone/1 ... ew-cockpit
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sprstdlyscottsmn

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Unread post21 Mar 2020, 02:35

That's a Silent Eagle CWB on the right, not a CFT
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eagle3000

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Unread post21 Mar 2020, 02:56

weasel1962 wrote:Well the CFT pylons can be removed...


CWB which is not part of the F-15EX program. Or any other advanced F-15 for that matter.

weasel1962 wrote:Wings were strengthened.
https://www.flightglobal.com/helicopter ... 93.article


Well yes, but not to reactivate stations 1/9. The F-15SA doesn't have the new wings but uses stations 1/9.
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aaam

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Unread post21 Mar 2020, 09:28

eagle3000 wrote:
weasel1962 wrote:Well the CFT pylons can be removed...


CWB which is not part of the F-15EX program. Or any other advanced F-15 for that matter.

weasel1962 wrote:Wings were strengthened.
https://www.flightglobal.com/helicopter ... 93.article


Well yes, but not to reactivate stations 1/9. The F-15SA doesn't have the new wings but uses stations 1/9.


That is my understanding as well. It was the new digital fly- by-wire flight control system that enabled activation of stations 1 and 9. Strengthening the wings permitted carrying greater loads, but it was the DFCS that allowed those stations to be used.
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Unread post21 Mar 2020, 13:29

The whole F-15C vs. E CFT issue is confusing as hell. Way back in 2017, USAF launched an experiment where National Guard F-15C's were fitted with CFT's under the, "persistent air dominance enabler" program. Well, were these F-15C CFT's? Because if they were, the pictured aircraft sure looks to be carrying the high drag/F-15E CFT's.

https://www.thedrive.com/the-war-zone/1 ... fuel-tanks

Nothing much has been said since?

Further, there are big discrepencies as to how much CFT's detract from performance. This article cites, "Conformal fuel tanks on the F-15C add nearly 12,000lbs of gas to the jets 13,850lbs of internal fuel with only slight performance penalties and are much more aerodynamically efficient than the 600 gallon drop tanks normally carried under the F-15C's wings and fuselage."

But it's also been mentioned they degrade performance significantly, and CFT's never caught on in CFT units because "unlike tanks, they couldn't be punched...".

So which is it?

I'd love to hear from an F-15C pilot who's flown with both (CFT's and tanks, which he prefers and why!)
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